Well, the way I see it you could:
- shift the song by a couple of octaves
- quit with an error
- replace those notes with silence along with warnings.
If you're shifting octaves, and the song still doesn't fit, maybe you should be able to define whether to keep the bottom or the top of the note spectrum. The song might play high notes to begin with, so you could just play that and skip the rest.
if a song has notes in the high and low range, it may just be impossible to convert. dunno what you really want to do.
- Nick